TL:DR
How were the fixed PE numbers calculated for Psychic Magic creatures?
Whilst comparing various creatures from The Occult Bestiary and Bestiary 5, I realised that the fixed PE numbers for Pyschic Magic appears, at first glance, to follow some hidden mathematical formula or is just applied as an arbitrary value.
I presumed it would follow the 10 + 1/2 HD + ability calculation. I'm going to presume Con for the ability as the Brain Mole has a Con of 13 for a +1 bonus.
For example :- B5
CR1 Brain Mole HD 2, CL 2nd = 12PE ( Base 10 + HD + Con ) seems okay
CR 5 Brain Mole Monarch HD 6, CL 6th = 16PE ( Base 10 + HD + Con +2 ) 15PE ?
CR 9 Caller in Darkness HD 13, CL 10th = 12PE ( Base 10 + HD + Cha +3 ) 19PE ?? Undead
Occult Bestiary
CR 5 Vayuphak, HD 8, CL 5th = 7PE ( Base 10 + HD + Con +1 ) 15PE????
CR 15 Uinuja, HD 18, CL 18th = 24PE ( Base 10 + HD + Con +6 ) 25PE?
and so forth.
So how were the numbers derived?
Max PE is typically at least 2.5x the highest level spell they can cast with psychic magic; more if they have a lot of options.
Thanks.
So how do the design team determine the additional PE to increase the 2.5x calculation by?
Just curious as it's not clearly laid out in the universal monster rules, similar to the majority of the UMR abilities.